A case of maternal uniparental disomy of chromosome 20 detected by noninvasive prenatal test of 1,000 high-risk pregnancies

Therefore, these discordant NIPT results can provide important leads to find UPD associated with confined placental mosaicism. Brady et al. [1] recommended the follow up discordant NIPT and invasive testing with UPD work up, particularly in cases where chromosomes 6, 7, 11, 14, 15, and 20 are involved because of the presence of known imprinting disorders related to these chromosomes. The maternal UPD 20 is substantially rare and the affected fetuses have a common feature of prenatal or postnatal growth delay [2-4]. Brady et al. [1] reported a total of 11 other chromosomal trisomies, involving all chromosomes except chromosomes 21, 18, and 13, detected using 4,000 NIPTs. Among them, six cases were followed up and four cases (two cases of trisomy 7 and one case each of trisomy 8 and trisomy 22) were revealed to have normal fetal karyotype in the amniotic fluid A case of maternal uniparental disomy of chromosome 20 detected by noninvasive prenatal test of 1,000 high-risk pregnancies